Clear URL with .htaccess - .htaccess

Question

I am pretty new to webdesign and haven't been able to figure this one out..
I am using HTML5Boilerplate as a template for my new website. The .htaccess file that ships with the template rewrites "www.example.com -> example.com". This is fine with me.
Now I would like to rewrite all my /index.html -> root folder and clear the slash at the end.
E.g.: when someone types or a link directs to "www.mysite.com/subfolder/index.html" (or .htm) this would get rewritten as "mysite.com/subfolder".
The code is at the moment:
# ----------------------------------------------------------------------
# Start rewrite engine
# ----------------------------------------------------------------------
# Turning on the rewrite engine is necessary for the following rules and
# features. FollowSymLinks must be enabled for this to work.
# Some cloud hosting services require RewriteBase to be set: goo.gl/HOcPN
# If using the h5bp in a subdirectory, use `RewriteBase /foo` instead where
# 'foo' is your directory.
# If your web host doesn't allow the FollowSymlinks option, you may need to
# comment it out and use `Options +SymLinksIfOwnerMatch`, but be aware of the
# performance impact: http://goo.gl/Mluzd
<IfModule mod_rewrite.c>
Options +FollowSymlinks
# Options +SymLinksIfOwnerMatch
RewriteEngine On
# RewriteBase /
</IfModule>
# ----------------------------------------------------------------------
# Suppress or force the "www." at the beginning of URLs
# ----------------------------------------------------------------------
# The same content should never be available under two different URLs -
# especially not with and without "www." at the beginning, since this can cause
# SEO problems (duplicate content). That's why you should choose one of the
# alternatives and redirect the other one.
# By default option 1 (no "www.") is activated.
# no-www.org/faq.php?q=class_b
# If you'd prefer to use option 2, just comment out all option 1 lines
# and uncomment option 2.
# IMPORTANT: NEVER USE BOTH RULES AT THE SAME TIME!
# ----------------------------------------------------------------------
# Option 1:
# Rewrite "www.example.com -> example.com".
<IfModule mod_rewrite.c>
RewriteCond %{HTTPS} !=on
RewriteCond %{HTTP_HOST} ^www\.(.+)$ [NC]
RewriteRule ^ http://%1%{REQUEST_URI} [R=301,L]
</IfModule>
# ----------------------------------------------------------------------
# Option 2:
# Rewrite "example.com -> www.example.com".
# Be aware that the following rule might not be a good idea if you use "real"
# subdomains for certain parts of your website.
# <IfModule mod_rewrite.c>
# RewriteCond %{HTTPS} !=on
# RewriteCond %{HTTP_HOST} !^www\..+$ [NC]
# RewriteRule ^ http://www.%{HTTP_HOST}%{REQUEST_URI} [R=301,L]
# </IfModule>

Answer 1

If you're serious about working with HTAccess, there is a very solid reference that will solve all the little thngs that might come up. It's not free - but will pay for itself.
http://htaccessbook.com

Answer 2

I think you can try this code:
RewriteEngine on
RewriteCond %{THE_REQUEST} ^.*\/index\.html?\ HTTP/
RewriteRule ^(.*)index\.html?$ "/$1" [R=301,L]
To remove the end slash add this code:
# remove trailing slash
RewriteRule ^(.*)\/(\?.*)?$ $1$2 [R=301,L]